The cerebellum is important for the control of movement, sensory processing, and regulation of cognitive and emotional function. In adulthood, damage to this region in adulthood leads to debilitating problems with everyday life; in infancy, cerebellar damage dramatically increases the risk of autism, a neurodevelopmental disorder. The long-term goal of this laboratory is to understand how early damage to the cerebellum can lead to symptoms of autism. In particular, the proposed experiments will use new technologies to study the function of individual cerebellar neurons that are involved in learning to anticipate predictable events in both awake mice, both normal and in mice with genetic defects that cause autism in humans. The overall objective of this application is to understand the function of the cerebellum in awake, behaving animals and then to use that information to understand how this circuit malfunctions in mouse models of autism spectrum disorder. This contribution is significant because it will produce detailed and integrated knowledge of the function of an important neural circuit under realistic conditions and apply that knowledge to a common neurodevelopmental disorder. This approach is innovative because this laboratory has developed tools that allow the study of cells that previously could not be examined in awake animals. The work proposed in this application will therefore advance knowledge of how the genetic mutations that cause autism influence the function of neural circuits. In the long run, this information could lead to new approaches to diagnosis, treatment, and prevention of autism spectrum disorder.